Businesses, residences, and other enterprises have come to rely on computing systems to access, generate and manage their key files, documents, and other operational data. Often, the data itself is many times more valuable to an enterprise than the computing hardware that stores the data. Accordingly, in this information age, many enterprises have taken precautions to protect their data.
One way of protecting data is to introduce storage redundancy. For example, a primary computing system maintains and operates upon the active data. Meanwhile, a backup computing system maintains a copy of the data. This may be accomplished by periodically taking a snapshot of the active data as that active data existed at the time of the snapshot, and by providing the snapshot copy of the protected data to a backup location on a periodic basis. For instances, snapshot-based backups often are configured to occur on a daily basis, though more or less frequent backup periods are also common. Should the active data be lost, the most recent backup copy of the data may be restored, thereby recovering the active data as the active data existed at the time of the last backup.
In some instances, however, it may be highly undesirable to lose all of the changes to the data that occurred since the time of the last snapshot backup. In such cases, Continuous Data Protection CDP may be more desirable. In CDP-based backup systems, an initial copy of the live data to be protected is captured and transferred to a backup medium. All subsequent writes to the live data are then time-stamped and journaled to the backup medium after each write operation. For instance, whenever a write operation occurs, the time, content, and target location of the write operation are documented in a data structure, which is then provided to the backup medium.
Since CDP-based backup systems back up and time stamp each block written to the protected data, it is possible to recover any state of the protected data since the time of the initial backup, in contrast to traditional snapshot-based backup systems which can recover only those states of the protected data that happen to exist at the time of the prior snapshot-based backup. This allows for a recovery back to any point in time to recover any version of a file.
Conventionally, CDP-based backup systems journal every block of every file modified on a volume, consuming large amounts of storage and requiring significant network bandwidth to replicate the journaled data to remote backup systems.